The 2013 Moore tornado was an EF5tornado that struck Moore, Oklahoma, and adjacent areas on the afternoon of May 20, 2013; with peak winds estimated at 210 mph (340 km/h), killing 24 people[1] (+1 indirect fatality) and injuring 377 others.[2][4][5] The tornado was part of a larger weather system that had produced several other tornadoes across the Great Plains over the previous two days (including five that struck Central Oklahoma on May 19). The tornado touched down west of Newcastle at 2:56 p.m. CDT (19:56 UTC), staying on the ground for 39 minutes over a 17-mile (27 km) path, crossing through a heavily populated section of Moore. The tornado was 1.3 miles (2.1 km) wide at its peak. Despite the tornado following a roughly similar track to the even deadlier 1999 Bridge Creek–Moore tornado, which was similar in size and severity, very few homes and neither of the stricken schools had purpose-built storm shelters.[2]

On May 20, 2013, a prominent central upper trough moved eastward with a lead upper low pivoting over the Dakotas and Upper Midwest region. A Southern stream shortwave trough and a moderately strong polar jet moved east-northeastward over the southern Rockies to the southern Great Plains and Ozarks area, with severe thunderstorms forming during the peak hours of heating. With the influence of moderately strong cyclonic flow aloft, the air mass was expected to become unstable across much of the southern Great Plains, Ozarks and middle Mississippi Valley by the afternoon.[6]

Evidence of an unstable air mass included dewpoints that ranged in the upper 60s °F (20 °C) to lower 70s °F (20–22 °C), temperatures in the low to mid 80s °F (27–30 °C), and CAPE values ranging from 3500–5000 J/kg. Deep-layer wind shear speeds of 40–50 kt would enhance storm organization and intensity.[7] These ingredients were present ahead of a cold front extending from a surface low in the eastern Dakotas, southwestward to near the Kansas City area and western Oklahoma, and ahead of a dry line extending from southwest Oklahoma southward into western north and west-central Texas. Outflow remnants from the previous night and early day convection across the Ozarks and middle Mississippi Valley were a factor in severe weather development with the most aggressive heating and destabilization on the western edge of this activity across the southern Great Plains and just ahead of a cold front.[6] The National Weather Service in Norman, Oklahoma, had warned as early as May 15 that there was a possibility of severe weather on May 20.[8]

The most intense severe weather activity was expected across the southern Great Plains, specifically Central Oklahoma, during the afternoon hours. As such, the Storm Prediction Center issued a moderate risk of severe thunderstorms during the early morning hours of May 20 from southeastern Missouri to north-central Texas. The degree of wind shear, moisture and instability within the warm sector favored the development of supercells. Very large hail and tornadoes were expected with the supercells, with the possibility of a few strong tornadoes.[6]

At 2:56 p.m. CDT, the tornado touched down in northeastern Grady County, roughly 4.4 miles (7.1 km) west of Newcastle, as an EF1 near the southwest corner of North Country Club Road and Northwest 32nd Street. The tornado caused EF1 damage to a home and some trees before rapidly intensifying and striking a semi-rural subdivision on the north side of Northwest 32nd where several homes were destroyed, two of which were leveled at EF4 intensity.[13] Slight ground scouring began in this area. Several homes in a subdivision further to the northeast sustained EF3 damage.[14][15] By 3:01 p.m. CDT, the National Weather Service issued a second, more strongly worded warning for the area: a tornado emergency was declared for southern Oklahoma City and Moore as storm spotters confirmed a large and violent tornado was approaching the area.[16] The tornado maintained EF3 intensity as it crossed the Canadian River into Cleveland County, and a decommissioned U.S. 62/U.S. 277 bridge was severely damaged; this bridge had to be demolished after the tornado ripped part of it from its mount and tossed it across Interstate 44.[17] The tornado then continued directly toward South Oklahoma City and Moore, roughly following Southwest 149th Street. At that point, it began to grow rapidly in width, and a second brief area of EF4 damage was noted near South May Avenue, where several homes were leveled, and one was swept clean from its foundation (this home was determined to have been nailed, rather than bolted to its foundation).[15] A vehicle frame, engine block, and various other vehicle parts were found tangled within a grove of completely debarked trees in this area.[18] The tornado weakened briefly to an EF3 before re-intensifying to EF4 intensity near Forman Drive, flattening several homes as it moved through mostly rural areas south of Southwest 149th Street. As the tornado struck an oil production site, four oil tanks were blown away, one of which was never found. The others were thrown considerable distances, one of which was found a mile away.[14][15]

The tornado maintained its intensity as it struck the Orr Family Farm and the Celestial Acres horse training area, where up to 100 horses were reported killed.[19] Every building at Celestial Acres sustained EF4 damage, along with a nearby strip mall.[14][15] Two 10-ton propane tanks on the Orr Farm property were picked up and thrown more than a half-mile by the tornado.[14][15][20] The tornado continued east, heavily scouring an open field before intensifying even further and slamming into Briarwood Elementary School, which was completely destroyed at EF5 intensity (though a 2014 study published by the American Meteorological Society revealed evidence of poor construction at the school, and the official EF5 rating at that location was disputed and listed as EF4 in the study). Remarkably, no fatalities occurred at the school.[14][21] Past Briarwood Elementary, the tornado entered densely populated areas of western Moore, including the Westmoor subdivision, where many well-built homes were flattened at EF4 intensity, and two were swept clean from their foundations, with damage at those two homes rated EF5.[15][22]

The tornado continued generally northeast at EF4 strength, debarking trees and leveling entire neighborhoods. Many homes were flattened in neighborhoods to the east of South Santa Fe Avenue.[23] One anchor-bolted home that was reduced to a bare slab in this area was initially rated EF5, but was later downgraded to EF4 as closer inspection of the foundation revealed that the anchor bolts were missing their nuts and washers.[24] The tornado then caused EF4 structural damage to Plaza Towers Elementary School, where seven children were killed. More than a dozen homes just south of Plaza Towers Elementary were swept cleanly away, though they were revealed to have been nailed rather than bolted to their foundations. Damage in that area was rated EF4 because of this. Most of the fatalities occurred in the Plaza Towers area.[14][15] In one of these houses (a block away from Plaza Towers), a woman was killed as she tried to seek shelter in a closet.[25] At least a dozen cars were piled up against the front entrance of the Moore Medical Center, which sustained EF4 damage. One car was lofted and thrown onto the roof. Many homes near the medical center were completely destroyed, including a row of four well-built homes with anchor bolts that were swept completely away, with damage to the four homes rated EF5. An open field directly behind this row of homes was scoured to bare soil, and a nearby manhole cover was removed.[26] The nearby Warren Theater was spared a direct hit, but still sustained considerable damage to its exterior.[15][21] A bowling alley in the area was leveled,[21] and a 7-Eleven was completely flattened, with four people killed inside (including one infant).[27] The nearby Moore Cemetery was heavily damaged as well.[28] The tornado briefly weakened and caused EF3 damage to some other businesses near Interstate 35, before crossing and mangling several vehicles in the process.[21] The tornado regained EF4 intensity on the other side of the Interstate as it tore through several neighborhoods and destroyed numerous additional homes (though the EF4 damage swath was narrower at this point).[21] A large grassy field between two subdivisions in this area was scoured to bare soil, with wind-rowed structural debris and several mangled vehicles strewn to the east.[29] One home on Hunters Glen Court sustained EF5 damage, with only the slab foundation and anchor bolts remaining and the debris scattered away from the site. Wind-rowing of debris was noted at that residence, and two vehicles were lofted from the site, one of which was thrown over 100 yards (91 m).[14][15]

The tornado continued through Moore's eastern neighborhoods. Highland East Jr. High's main building was spared, but the separate gymnasium building was completely destroyed, and a set of lockers from the structure was lofted and thrown a considerable distance into a nearby neighborhood.[23] The tornado was noticeably narrower at this point, but was still causing EF3 and EF4 damage to numerous homes as it moved through multiple subdivisions. A well-built, anchor-bolted home at the corner of Heatherwood Drive and Southeast 5th Street was reduced to a bare slab, sustaining EF5 damage.[14][23] A large, well-bolted-down home at the end of a private drive near South Olde Bridge Road was also swept cleanly away at EF5 intensity. Debris was scattered well away from the site, a vehicle was thrown over 100 yards, and wind-rowing was again noted at that location.[15] Further east, the tornado weakened to EF3 strength and exited the most populated parts of Moore, destroying six industrial buildings and damaging two others. A final small area of EF4 damage was noted nearby as two homes and a concrete building were leveled.[15] The tornado then began to rapidly narrow and weaken, snapping and uprooting several trees and causing EF2 damage to a farm just east of Moore, where the house lost its roof and an outbuilding was destroyed. A pickup truck slid 200 feet (61 m) away from the farm into a field while remaining upright. The tornado dissipated at a nearby treeline.[14][15]

The Oklahoma Department of Emergency Management reported that 24[30] people were killed (with another indirect), with an estimated 1,150 homes destroyed, and an estimated $2 billion in damages.[3] The number of injured was 377.[31] Entire subdivisions were obliterated, and houses were flattened in a large swath of the city. The majority of a neighborhood just west of the Moore Medical Center was destroyed.[32] Witnesses said the tornado more closely resembled "a giant black wall of destruction" than a typical twister.[33]

Among the hardest hit areas were two public schools: Briarwood Elementary School and Plaza Towers Elementary School. At the latter school, 75 children and staff were present when the tornado struck.[34] Seven children died at Plaza Towers Elementary School.[35] A preliminary study on Briarwood Elementary School conducted in September 2013 by a group of structural engineers found some structural deficiencies that led to its collapse during the tornado. Chris Ramseyer, a structural engineer and an associate professor at the University of Oklahoma determined that the building's walls that were not reinforced with concrete, there had been a lack of connection between the masonry walls and support beams in several portions of the building, and anchor bolts were pulled from the ground by the tornado. Another engineer that was involved in the study stated that the deficiencies that Ramseyer pointed out were not uncommon building practices at the time, and that current building code standards would not ensure that Briarwood would have withstood winds in excess of 200 mph.[36]

The Moore Medical Center was heavily damaged, but no one present in the building was injured by the tornado. The center's staff had to relocate 30 patients to a hospital in Norman and another hospital.[37] Part of Interstate 35 was shut down due to debris that had been thrown onto the freeway.[38] On May 21, Moore still did not have running water.[39] There were more than 61,500 power outages related to the tornado.[40] More than 100 people were rescued from areas that sustained significant damage from the tornado.[41]

Over a dozen emergency workers comb through the rubble of a destroyed building.

Within the first two days, it was reported that between 237[44] and 240 people had been injured, with the tally later increasing to over 350.[45][46] On the morning of May 21, the medical examiner's office incorrectly stated that 91 bodies of tornado victims had been received.[47] This number was up from the earlier report of 51 bodies that were incorrectly stated as having been received. The actual number was later confirmed at 24 tornado victims and one indirect victim. A 90-year-old woman who suffered a fractured skull during the tornado later suffered a pair of strokes and died on August 5.[4][5][30][35] The 2013 Moore tornado was the deadliest tornado recorded in the U.S. since the Joplin, Missouri tornado that killed 158 people in May 2011.[48]

President Obama declared a major disaster in the state, ordering federal aid to the affected areas:[54]Cleveland, Lincoln, McClain, Oklahoma, and Pottawatomie Counties; funding for hazard mitigation measures was included in the declaration to be made available statewide.[55] Obama visited the disaster-stricken areas on May 26.[56]

Major structural damage at Briarwood Elementary School.

The third season finale of the sitcom Mike & Molly, titled "Windy City", was pulled by CBS from its original May 20 airdate within hours of the event due to the episode featuring a plotline involving a tornado descending on Chicago; the network later rescheduled the episode to air ten days later on May 30, 2013.[57][58]

On June 2, 2013, Discovery Channel aired an hour-long documentary about the storm titled Mile-Wide Tornado: Oklahoma Disaster. The documentary provides a comprehensive look at the tornado's impact and drew comparisons of the storm to the 1999 Bridge Creek-Moore tornado.[77]

The Moore City Council proposed a measure making twelve changes to its residential building codes, include requiring that new home construction in the city include hurricane clips or framing anchors, continuous plywood bracing and wind-resistant garage doors in order for homes to withstand winds up to 135 mph (equivalent to a high-end EF2 tornado). When the measure was passed in a unanimous vote held on March 17, 2014, Moore became the first city in the United States to adopt a building code addressing the effects of tornadoes on homes, which exceed the national standards set by the National Association of Home Builders.[78][79]

1. These are the unadjusted damage totals in millions of US dollars.
2. Raw damage totals adjusted for inflation, in millions of 2015 USD.
3. A search of NCDC Storm Data indicates no tornadoes between 1999 and 2010 have caused more than $400 million in damage.